Catheter With Deflectable Tip

ABSTRACT

A catheter having a distal balloon and a deformable guidewire shaft of the catheter. The deformable guidewire shaft is adjacent to and external to the balloon. Inflation of the balloon bends the deformable guidewire shaft in order to orient or deflect a distal tip of the deformable guidewire shaft in a desired direction to guide and direct a guidewire extending through the deformable guidewire shaft towards a specific endovascular region. For example, it may be desired to orient the distal tip of the guidewire shaft towards a target vessel of a bifurcation or the balloon catheter may be used to bypass a Chronic Total Occlusion (CTO).

FIELD OF THE INVENTION

The invention relates in general to catheters and in particular to aballoon catheter having a deflectable distal end.

BACKGROUND OF THE INVENTION

A variety of catheters for delivering a therapy and/or monitoring aphysiological condition have been implanted or proposed for implantationin patients. Catheters may deliver therapy to, and/or monitor conditionsassociated with, the heart, muscle, nerve, brain, stomach or otherorgans or tissue. Many catheters are tracked through the vasculature tolocate a therapeutic or diagnostic portion of the catheter at a targetsite. Such catheters must have flexibility to navigate the twists andturns of the vasculature, sufficient stiffness in the proximal portionthereof to be pushed through the vasculature alone or over a guidewireor through a lumen, and the capability of orienting a distal portionthereof in alignment with an anatomical feature at the target site sothat a diagnostic or therapeutic procedure can be completed. In generalterms, the catheter body must also resist kinking and be capable ofbeing advanced through access pathways that twist and turn, sometimesabruptly at acute angles.

The distal portions of catheters frequently need to be selectivelydeflected or bent and straightened again while being advanced within thepatient to steer the catheter distal end into a desired body lumen orchamber. For example, it may be necessary to direct the catheter distalend through tortuous anatomies and/or into a branch of vesselbifurcation. In addition, some procedures require high accuracy inguidewire orientation. For example, when a subintimal approach isselected for crossing a Chronic Total Occlusion (CTO), a guidewire needsto be accurately oriented to re-enter the true vessel lumen downstreamof the CTO. Various steerable mechanisms have been disclosed to steercatheters and other elongated medical devices, e.g., steerableguidewires and stylets, and often involve the use of a deflectionmechanism extending through a lumen of the catheter body to anattachment point in the catheter distal portion. For example, adeflection mechanism may include elongated wires referred to as controlor pull wires, extending between a proximal control mechanism and thedistal attachment point. More complex steerable catheters have two ormore lumens and control wires extending from the handle to differentpoints along the length or about the circumference of the catheter bodyto induce bends in multiple segments of the catheter body and/or indifferent directions.

Embodiments hereof are directed to a catheter having deflectable tip fornavigating through or within a patient's anatomy.

BRIEF SUMMARY OF THE INVENTION

Embodiments hereof are directed to a balloon catheter including a maincatheter shaft, a deformable guidewire shaft, and a balloon. The maincatheter shaft includes a guidewire lumen and an inflation lumen. Thedeformable guidewire shaft extends from a distal end of the maincatheter shaft, adjacent and external to the balloon, and the deformableguidewire shaft defines a lumen in fluid communication with theguidewire lumen of the main catheter shaft. The balloon extends from adistal end of the main catheter shaft and the inflation lumen of themain catheter shaft is in fluid communication with an interior of theballoon. A proximal bond fixes a proximal end of the balloon to a distalend of the main catheter shaft and a distal bond fixes a distal end ofthe balloon to a distal end of the deformable guidewire shaft, whereinan outer surface of the deformable guidewire shaft between the proximalbond and the distal bond is not bonded to the balloon. Balloon inflationcauses the balloon and the deformable guidewire shaft to bend inradially opposing directions, thereby orienting the distal end of thedeformable guidewire shaft in a direction different from that of themain catheter shaft.

Embodiments hereof are also related to a method of orienting a distalend of a balloon catheter in situ. The balloon catheter includes a maincatheter shaft, a deformable guidewire shaft extending from a distal endof the main catheter shaft, and a balloon extending from a distal end ofthe main catheter shaft. The deformable guidewire shaft is adjacent andexternal to the balloon. A proximal bond fixes a proximal end of theballoon to a distal end of the main catheter shaft, a distal bond fixesa distal end of the balloon to a distal end of the deformable guidewireshaft, and an outer surface of the deformable guidewire shaft betweenthe proximal and distal bonds is not coupled to the balloon. Thedeformable guidewire shaft defines a lumen in fluid communication with aguidewire lumen of the main catheter shaft and an inflation lumen of themain catheter shaft is in fluid communication with an interior of theballoon. The balloon catheter is percuataneously advanced through avasculature to a target location. The balloon is inflated, and ballooninflation causes the balloon and the deformable guidewire shaft to bendin radially opposing directions, thereby orienting the distal end of thedeformable guidewire shaft in a direction different from that of themain catheter shaft.

BRIEF DESCRIPTION OF DRAWINGS

The foregoing and other features and advantages of the invention will beapparent from the following description of embodiments hereof asillustrated in the accompanying drawings. The accompanying drawings,which are incorporated herein and form a part of the specification,further serve to explain the principles of the invention and to enable aperson skilled in the pertinent art to make and use the invention. Thedrawings are not to scale.

FIG. 1 is a side view of a catheter having a balloon and a deformableguidewire shaft according to an embodiment hereof, the balloon beingproximally bonded to a main catheter shaft and distally bonded to thedeformable guidewire shaft, wherein the balloon is in a delivery ordeflated configuration.

FIG. 1A is a cross-sectional view taken along line A-A of FIG. 1.

FIG. 1B is a cross-sectional view taken along line A-A of FIG. 1according to another embodiment hereof in which the main catheter shaftis formed via multi-lumen extrusion.

FIG. 2 is a side view of a distal portion of the catheter of FIG. 1,wherein the balloon is in a deployed or inflated configuration andballoon inflation causes a distal end of the deformable guidewire shaftto bend or deflect with respect to the main catheter shaft.

FIG. 3 is a side view of a distal portion of a catheter having a balloonand a deformable guidewire shaft according to another embodiment hereof,the deformable guidewire shaft being a coiled shaft, wherein the balloonis in a delivery or deflated configuration.

FIG. 4 is a side view of a distal portion of a catheter having a balloonand a deformable guidewire shaft according to another embodiment hereof,the catheter including a radiopaque marker within the balloon, whereinthe balloon is in a deployed or inflated configuration.

FIG. 5 is a side view of a distal portion of a catheter having a balloonand a deformable guidewire shaft according to another embodiment hereof,the catheter including additional bonds between intermediate portions ofthe balloon and the deformable guidewire shaft, wherein the balloon isin a deployed or inflated configuration.

FIG. 6 is a side view of a distal portion of a catheter having a balloonand a deformable guidewire shaft according to another embodiment hereof,wherein intermediate portions of the balloon and the deformableguidewire shaft may be selectively magnetically coupled together and theballoon is in a delivery or deflated configuration.

FIG. 6A is a side view of the catheter of FIG. 6, wherein intermediateportions of the balloon and the deformable guidewire shaft areselectively magnetically coupled and the balloon is in a deployed orinflated configuration.

FIG. 6B is a side view of the catheter of FIG. 6, wherein intermediateportions of the balloon and the deformable guidewire shaft are notmagnetically coupled and the balloon is in a deployed or inflatedconfiguration.

FIG. 7 is a side view of a distal portion of a catheter having a balloonand two deformable guidewire shafts according to another embodimenthereof, wherein the balloon is in a delivery or deflated configuration.

FIG. 7A is a cross-sectional view taken along line A-A of FIG. 7.

FIG. 7B is a side view of the catheter of FIG. 7, wherein the balloon isin a deployed or inflated configuration.

FIGS. 8A-8C illustrate a method of using the catheter of FIG. 6 at abifurcation.

FIGS. 9A-9F illustrate a method of using the catheter of FIG. 6 tobypass a chronic total occlusion (CTO).

DETAILED DESCRIPTION OF THE INVENTION

Specific embodiments of the present invention are now described withreference to the figures, wherein like reference numbers indicateidentical or functionally similar elements. The terms “distal” and“proximal” are used in the following description with respect to aposition or direction relative to the treating clinician. “Distal” or“distally” is a position distant from or in a direction away from theclinician. “Proximal” or “proximally” is a position near or in adirection toward the clinician.

The following detailed description is merely exemplary in nature and isnot intended to limit the invention or the application and uses of theinvention. Although the description of the invention is in the contextof treatment of blood vessels such as the coronary, carotid and renalarteries, and in general the peripheral vasculature (e.g. femoral andpopliteal arteries), the invention may also be used in any other bodypassageways where it is deemed useful. Furthermore, there is nointention to be bound by any expressed or implied theory presented inthe preceding technical field, background, brief summary or thefollowing detailed description.

Embodiments hereof relate to a catheter having a distal balloon and adeformable guidewire shaft which is adjacent and external to theballoon. Inflation of the balloon deflects or bends the deformableguidewire shaft in order to orient or angle a distal end of theguidewire shaft in a desired direction to guide and direct a guidewireextending through the deformable guidewire shaft towards a specificendovascular region.

More particularly, with reference FIG. 1, FIG. 1A, and FIG. 2, a ballooncatheter 100 includes a main or elongated catheter shaft 102 defining alumen 104, an inflatable balloon 122, and a deformable guidewire shaft114 defining a lumen 116 and being positioned adjacent and external toballoon 122. Deformable guidewire shaft 114 extends longitudinally alongan exterior surface of balloon 122. Balloon 122 is shown in anunexpanded or delivery configuration in FIG. 1 and is shown in anexpanded or inflated configuration in FIG. 2. In the catheterconstruction of the embodiment shown in FIGS. 1 and 1A, a guidewireshaft or tube 106 defining a lumen 108 and an inflation shaft or tube110 defining an inflation lumen 112 extends through lumen 104 of maincatheter shaft 102. Deformable guidewire shaft 114 is coupled to andextends from a distal end 107 of main catheter shaft 102 so that itforms a continuation or extension of guidewire shaft 106 and lumen 116of deformable guidewire shaft 114 is in fluid communication with lumen108 of guidewire shaft 106. As such, guidewire shaft 106 and deformableguidewire shaft 114 collectively define a guidewire lumen that extendssubstantially the entire length of the catheter for accommodating aguidewire (not shown in FIG. 1). Other types of catheter constructionare also amendable to the invention, such as, without limitationthereto, a catheter shaft formed by multi-lumen profile extrusion asshown in FIG. 1B in which a main catheter shaft 102B is a dual lumentubular component that includes an inflation lumen 112B and a guidewirelumen 108B. In another embodiment hereof (not shown), catheter 100 maybe modified to be of a rapid exchange (RX) catheter configurationwithout departing from the scope of the present invention such thatguidewire shaft 106 extends within only the distal portion of maincatheter shaft 102.

Main catheter shaft 102 has a proximal end 118, which also defines aproximal end of catheter 100, which extends out of the patient and iscoupled to a hub 103. Distal end 107 of main catheter shaft 102 iscoupled to a proximal end or neck 124 of balloon 122. A distal end orneck 126 of balloon 122 is coupled to a distal end 120 of deformableguidewire shaft 114, which defines a distal guidewire port as well as adistal end of catheter 100. Distal end 120 may include a tapered distalcatheter tip (not shown).

Inflation lumen 112 extends between proximal and distal ends 118, 107,respectively, of main catheter shaft 102 to allow inflation fluidreceived through hub 103 to be delivered to balloon 122. As would beunderstood by one of ordinary skill in the art of balloon catheterdesign, hub 103 provides a luer hub or other type of fitting that may beconnected to a source of inflation fluid and may be of anotherconstruction or configuration without departing from the scope of thepresent invention.

The catheter shafts, including main catheter shaft 102, guidewire shaft106, and inflation shaft 110, may be formed of a polymeric material,non-exhaustive examples of which include polyethylene, polyethyleneblock amide copolymer (PEBA), polyamide and/or combinations thereof,either laminated, blended or co-extruded. Optionally, main cathetershaft 102 or some portion thereof may be formed as a composite having areinforcement material incorporated within a polymeric body in order toenhance strength and/or flexibility. Suitable reinforcement layersinclude braiding, wire mesh layers, embedded axial wires, embeddedhelical or circumferential wires, hypotubes, and the like. In oneembodiment, for example, at least a proximal portion of main cathetershaft 102 may be formed from a reinforced polymeric tube.

Balloon 122 is fixed to catheter 100 via two constraints, a proximalbond 128 and a distal bond 130. An outer surface of deformable guidewireshaft 114 between the proximal and distal bonds is not bonded orotherwise coupled to balloon 122. Proximal bond 128 fixes or couplesproximal end 124 of balloon 122 to main catheter shaft 102, andinflation lumen 112 of main catheter shaft 102 is in fluid communicationwith the interior of balloon 122. Distal bond 130 fixes or couplesdistal end 126 of balloon 122 to a distal end 120 of deformableguidewire shaft 114. The distance or length between proximal and distalbonds 128, 130, in which balloon 122 and deformable guidewire shaft 114are not coupled together, is equal to or slightly less than the lengthof balloon 122 prior to inflation thereof. More particularly, in anembodiment, balloon 122 may have a length of 10-60 mm and the distanceor length between proximal and distal bonds 128, 130 may be between 80and 90% of the balloon length. The distance between proximal and distalbonds 128, 130 is a function of the amount of desired bending needed,i.e., a shorter distance results in less bending. Proximal and distalbonds 128, 130 may be formed in any conventional manner known to one ofskill in the art of balloon catheter construction, such as by laserwelding, adhesives, heat fusing, or ultrasonic welding.

Referring now to FIG. 2, inflation of balloon 122 causes balloon 122 anddeformable guidewire shaft 114 to bend, curve, or bow in radiallyopposing directions, thereby orienting or deflecting distal end 120 ofdeformable guidewire shaft 114 in a direction different from that of themain catheter shaft 102. More particularly, prior to inflation or in adeflated state, both balloon 122 and deformable guidewire shaft 114 arestraight and have a first longitudinal length. Balloon 122 is formed ofa compliant or semi-compliant material and as balloon 122 inflates,pressure stretches the balloon walls in both the radial and longitudinaldirections. As a result, as balloon 122 inflates, the longitudinallength of the balloon increases from the first longitudinal length to asecond longitudinal length, which is greater than the first longitudinallength, and a diameter of the balloon increases from a first diameter toa second diameter. Such stretching is achieved due to the capability ofpolymer fibers of the balloon material to align and withstand inflationpressures. On the other hand, deformable guidewire shaft 114 maintainsthe same length and diameter, i.e., the length and diameter ofdeformable guidewire shaft 114 does not change during balloon inflation.Since proximal and distal ends 124, 126 of balloon 122 are constrainedor fixed via proximal and distal bonds 128, 130, inflation of balloon122 causes the balloon to bend or bow as the longitudinal length of theballoon increases from the first longitudinal length to the secondlongitudinal length. Meanwhile, in order to balance the forces developedduring balloon inflation, deformable guidewire shaft 114 bends or bowswith its concavity directed towards balloon 122. As a result, distal end120 of deformable guidewire shaft 114 is oriented in a directiondifferent from that of main shaft 102. Hence, as a function of theballoon inflation, during the procedure a guidewire which is insertedthrough the guidewire lumen can be oriented according to differentdirections, in particular different from the longitudinal straightdirection collectively defined by guidewire shaft 106 and deformableguidewire shaft 114.

The amount of deflection or bending of deformable guidewire shaft 114 isdependent upon various factors including inflation pressure, ballooncompliance, and material characteristics of deformable guidewire shaft114. Most notably, the amount of deflection or bending of deformableguidewire shaft 114 is a function of inflation pressure. In general, themore balloon 122 is inflated, the greater amount of bending ordeflection occurs or is produced in deformable guidewire shaft 114.

Compliance of balloon 122 also affects the amount of deflection orbending of deformable guidewire shaft 114. Balloon compliance can bedefined as the change in balloon diameter and length as a function ofinflation pressure. A high compliant balloon has a relatively largeincrease in diameter and length in response to an increase in inflationpressure, while a balloon having a relatively small increase in diameterand length in response to an increase in inflation pressure is said tobe a low compliant balloon or a non-compliant balloon. In general,higher balloon compliance results in more deflection or bending ofballoon 122, which in turn results in more deflection or bending ofdeformable guidewire shaft 114. As such, balloon 122 is formed from acompliant or semi-compliant material in order to result in the desiredbending thereof. Non-exhaustive examples of materials for balloon 122include polymers such as polyethylene, PEBA, polyethylene terephthalate(PET), polyamide, and polyurethane, copolymers or blends thereof. In oneembodiment, balloon 122 is a relatively compliant thermoplasticelastomer (TPE) material. The size of balloon 122 will vary according toapplication. However, in an embodiment hereof, the second longitudinallength of balloon 122 in an inflated or expanded state is between 10 and60 mm and the second diameter of balloon 122 in an inflated or expandedstate is between 1 and 3 mm in order to minimize the size of the distalportion of catheter 100 when balloon 122 is inflated in situ.

In addition to material properties of balloon 122, material propertiesof deformable shaft extension 114 also affect the amount of deflectionor bending of deformable guidewire shaft 114. The material and themechanical characteristics of deformable guidewire shaft 114 are chosento optimize the deformability or flexibility thereof. For this reason,deformable guidewire shaft 114 is a separate component from guidewireshaft 106 and has different material properties from guidewire shaft106. A proximal end of deformable guidewire shaft 114 is coupled to adistal end of guidewire shaft 106 to form a continuous guidewire lumenas described above. However, in another embodiment hereof (not shown),guidewire shaft 114 and guidewire shaft 106 may be a continuous shaft ortube of the same material. In order to ensure that deformable guidewireshaft 114 bends in response to balloon inflation while main shaft 102remain straight, deformable guidewire shaft 114 is constructed such thatthe bending stiffness M_(G) thereof is lower than bending stiffnessM_(M) of main shaft 102. In an embodiment hereof, bending stiffnessM_(G) of deformable guidewire shaft 114 is approximately equal to or inthe same range as the bending stiffness of balloon 122 in order toguarantee a sufficient bending rate while inflating the balloon. Bendingstiffness may be defined as M=EJ, where E is the elastic modulus of thematerial and J is the cross section moment of inertia.

The target bending stiffness M_(G) of deformable guidewire shaft 114 maybe achieved either by means of a proper geometrical construction ofdeformable guidewire shaft 114 and/or by means of selecting a particularmaterial for deformable guidewire shaft 114. With respect to thegeometrical construction of deformable guidewire shaft 114, it isdesirable to reduce or minimize the cross section moment of inertia byreducing or minimizing inner and outer diameters of deformable guidewireshaft 114 or, if deformable guidewire shaft 114 has a non-circular crosssection, changing geometrical characteristics of the cross section ofdeformable guidewire shaft 114. However, the size of lumen 116 ofdeformable guidewire shaft 114 must remain of sufficient size toaccommodate a guidewire.

With respect to selection of a particular material for deformableguidewire shaft 114, it is desirable to reduce or minimize the elasticmodulus of the material. The elastic modulus of the material fordeformable guidewire shaft 114 may vary between 0.01-10 GPa.Non-exhaustive examples of materials for deformable guidewire shaft 114include a polyether block amide (PEBA) and a standard polyamide such asNylon 12, Nylon 66. Selection of material for deformable guidewire shaft114 may occur after balloon material and size are selected. For example,if a relatively small balloon is selected, e.g. a standard nylonballoon, 10 mm length, 1 mm nominal diameter, the expected amount oflongitudinal compliance recovered during inflation is small andaccordingly, material selection deformable guidewire shaft 114 would bea very soft material having a low elastic modulus.

In an embodiment hereof, shown in FIG. 3, a coil 340 may be wrappedaround an outermost surface of deformable guidewire shaft 114 in orderto enhance flexibility and allow for proper bending thereof withoutkinking. Pitch length and wire characteristics of coil 340 may be chosenor designed to increase bending performance. For example, coil 340 maybe constructed with a ribbon or flat wire, or with a round wire, toincrease bending performance thereof. A round wire having a circularcross section may reduce friction between adjacent windings of coil 340.Pitch or pitch length between windings of coil 340 may vary in a rangeof 0.005-0.05 inches. Pitch may be chosen or designed in order toprovide the desired stiffness of coil. In general, a shorter pitch inwhich the windings of coil 340 are relatively close together results inincreased stiffness. According to another embodiment hereof, rather thanhaving a coil wrapped around deformable guidewire shaft 114, thedeformable guidewire shaft itself may be a coil or may have a coilconstruction. For example, a coil may be co-extruded with a polymerictube that forms or makes the deformable guidewire shaft.

It may be desirable to monitor the position of balloon 122 duringinflation in order to determine whether additional inflation and bendingthereof is required. Thus, in an embodiment shown in FIG. 4, catheter100 may include a relatively small shaft or tube 442 having a radiopaquemarker band 444 mounted on or adjacent to its distal end 446. A proximalend 448 of tube 442 is positioned within inflation lumen 112 of mainshaft 102 and is fixed or coupled to an inside surface of inflation tube110. Distal end 446, having marker band 444 thereon, extends distallyand protrudes into balloon 122. Distal end 446 is not constrained orcoupled to balloon 122, but an intermediate bond 450 may be included tocouple tube 442 to a distal portion of main shaft 102 and/or a proximalportion of balloon 122. During balloon inflation, distal end 446 of tube442 follows or moves with balloon 122, thus providing a visualindication of the position of balloon 122. In addition to marker 444,additional radiopaque markers (not shown) may be placed on main shaft102 and/or deformable guidewire shaft 114. Additional radiopaque markersallow visibility of position/orientation of the balloon with respect tothe position/orientation of the main shaft and/or deformable guidewireshaft. Further, according to another embodiment (not shown), tube 442may be omitted and inflation tube 110 may extend into and within balloon122, distal to proximal bond 128, and a radiopaque marker band may bemounted adjacent to a distal end of inflation tube 110.

During some procedures, it may be desirable for the balloon and thedeformable guidewire shaft to bend, curve, or bow in the same radialdirection rather than radially opposing directions as described withrespect to FIG. 2. Referring to FIG. 5, another embodiment hereof isshown in which two additional bonds 552A, 552B are provided between aballoon 522 and a deformable guidewire shaft 514 which force thedeformable guidewire shaft to bend in the same direction as the balloon.Additional bonds 552A, 55B are positioned between proximal and distalbonds 528, 530, which have placement and function similar to proximaland distal bonds 128, 130 described above. Although FIG. 5 illustratestwo additional bonds to couple an intermediate or middle portion ofdeformable guidewire shaft 514 to an intermediate or middle portion ofballoon 522, a greater or less number of additional bonds may be used.Since the intermediate or middle portion of deformable guidewire shaft514 remains connected or coupled to balloon 522 through additionalconstraints, i.e., bonds 552A, 552B, deformable guidewire shaft 514starts bending with its concavity directed in the same direction as theconcavity of the balloon. Additional bonds 552A, 55B may be formed inany conventional manner known to one of skill in the art of ballooncatheter construction, such as by laser welding, adhesives, heat fusing,or ultrasonic welding.

According to further embodiments hereof, a balloon catheter includes adeformable guidewire shaft that has the capability to bend in the samedirection as the balloon and/or in a radially opposing direction as theballoon. The bending direction may be selectively decided in situ by theoperator. More particularly, a balloon catheter 600 is shown in FIG. 6.Similar to balloon catheter 100, balloon catheter 600 includes a maincatheter shaft 602 having a guidewire lumen (not shown) and an inflationlumen (not shown), a deformable guidewire shaft 614, and a balloon 622.Deformable guidewire shaft 614 extends from a distal end 607 of maincatheter shaft 602, adjacent and external to balloon 622, and thedeformable guidewire shaft defines a lumen in fluid communication withthe guidewire lumen of the main catheter shaft. Balloon 622 extends fromdistal end 607 of main catheter shaft 602, and the inflation lumen ofthe main catheter shaft is in fluid communication with an interior ofthe balloon. Also similar to balloon catheter 100, a proximal bond 628fixes a proximal end of the balloon to distal end 607 of main cathetershaft 602 and a distal bond 630 fixes a distal end of balloon 622 to adistal end 620 of deformable guidewire shaft 614. An outer surface ofdeformable guidewire shaft 614 between proximal bond 628 and the distalbond 630 is not bonded to balloon 622.

The bending direction of deformable guidewire shaft 614 may beselectively decided in situ by the operator via first and secondmagnetic components 660, 662. First magnetic component 660 iscoupled/bonded to or insertable within or over an intermediate portionof balloon 622, and second magnetic component 662 is coupled to orinsertable within or over an intermediate portion of deformableguidewire shaft 614. The first and second magnetic components areoperable to selectively and temporarily couple the intermediate portionof balloon 622 and the intermediate portion of deformable guidewireshaft 614 together. Coupling between balloon 622 and deformableguidewire shaft 614 is selectively achieved by means of the magneticforce between first and second magnetic components 660, 662. When theintermediate portions of the balloon and deformable guidewire shaft arecoupled together and balloon 622 is inflated, first and second magneticcomponents 660, 662 operate or function similar to additional bonds552A, 552B described with respect to FIG. 5 and cause deformableguidewire shaft 614 to bend in the same direction as balloon 622 asshown in FIG. 6A. However, as shown in FIG. 6B, when the intermediateportions of the balloon and deformable guidewire shaft are not coupledtogether and balloon 622 is inflated, balloon 622 and deformableguidewire shaft 614 bend in radially opposing directions as describedwith respect to FIG. 2.

In a first embodiment, in order to provide catheter 600 and deformableguidewire shaft 614 with the capability of selectively bending in one oftwo opposing directions, first magnetic component 660 is coupled to adistal end of an elongate component 664 that is slidingly insertablewithin the inflation lumen of catheter 600 in order to position firstmagnetic component 660 at an intermediate portion of balloon 622. Secondmagnetic component 662 is coupled to an inner or outer surface ofdeformable shaft component 614. Alternatively, in another embodiment(not shown), first magnetic component 660 may be coupled to a surface ofballoon 622 or may be coupled to an interior tube that extends intoballoon 622, such as tube 442 described with respect to FIG. 4, andsecond magnetic component 662 may be selectively insertable intodeformable shaft component 614. Both first and second magneticcomponents 660, 662 may be formed from a magnetic material, or one offirst and second magnetic components 660, 662 is formed from a magneticmaterial and the other is formed from a ferromagnetic material.

In a second embodiment, in order to provide catheter 600 and deformableguidewire shaft 614 with the capability of selectively bending in one oftwo opposing directions, first magnetic component 660 is anelectromagnet while second magnetic component 662 is formed from aferromagnetic material. An electromagnet is a type of magnet in which amagnetic field is produced by the flow of electric current. When thecurrent is turned on, the electromagnet creates a magnetic field andwhen the current is turned off, the electromagnet does not create amagnetic field. As such, coupling between the intermediate portions ofthe balloon and deformable guidewire shaft can be selectively activatedby turning the electric current flowing into the electromagnet on oroff. In this embodiment, an elongated conductor 666 such as a wireextends through the inflation lumen of catheter 600 and connects theelectromagnetic, which is magnetic components 660, to an externalcurrent generator (not shown) which is located external to the catheter.Alternatively, in another embodiment (not shown), second magneticcomponent 662 is the electromagnet and first magnetic component 660 isformed from a ferromagnetic material.

FIG. 7 illustrates another embodiment hereof in which a balloon catheter700 includes two deformable guidewire shafts which bend in opposingdirections so that the direction of a guidewire inserted there throughmay be selectively decided in situ by the operator. Balloon catheter 700includes a main catheter shaft 702, a first deformable guidewire shaft714A, a second deformable guidewire shaft 714B, and a balloon 722. Asshown in FIG. 7A, main catheter shaft 702 includes a first guidewirelumen 706A, a second guidewire lumen 706B, and an inflation lumen 712.First deformable guidewire shaft 714A extends from a distal end 707 ofmain catheter shaft 702, adjacent and external to balloon 722, and thefirst deformable guidewire shaft defines a lumen 716A in fluidcommunication with first guidewire lumen 706A of main catheter shaft702. Second deformable guidewire shaft 714B also extends from distal end707 of main catheter shaft 702, adjacent and external to balloon 722,and the second deformable guidewire shaft defines a lumen 716B in fluidcommunication with second guidewire lumen 706B of main catheter shaft702. Balloon 722 also extends from distal end 707 of the main cathetershaft, and inflation lumen 712 of main catheter shaft 702 is in fluidcommunication with an interior of balloon 722.

Essentially, first deformable guidewire shaft 714A is coupled to balloon722 in the same manner as guidewire shaft 114 described with respect toFIGS. 1-2, while second deformable guidewire shaft 714B is coupled toballoon in the same manner as guidewire shaft 514 described with respectto FIG. 5. More particularly, a proximal bond 728 fixes a proximal endof balloon 722 to distal end 707 of main catheter shaft 702. Firstdistal bond 730A fixes a distal end of balloon 722 to distal end 720A offirst deformable guidewire shaft 714A, and second distal bond 730B fixesdistal end 720A of first deformable guidewire shaft 714A to distal end720B of second deformable guidewire shaft 714B, thereby coupling thedistal ends of balloon 722 and first and second deformable guidewireshafts 714A, 714B together. In another embodiment hereof (not shown),the distal end of balloon 722 may be coupled to each distal end 720A,720B, of first and second deformable guidewire shafts 714A, 714B,respectively. Regardless of the particular construction, the distal endsof balloon 722 and first and second deformable guidewire shafts 714A,714B are coupled or bonded together. An outer surface of firstdeformable guidewire shaft 714A between proximal bond 728 and firstdistal bond 730A is not bonded to the balloon, while at least oneintermediate bond 752 fixes an intermediate portion of balloon 722 to anintermediate portion of second deformable guidewire shaft 714B. Similarto deformable guidewire shaft 114, balloon inflation causes balloon 722and first deformable guidewire shaft 714A to bend in radially opposingdirections while, similar to deformable guidewire shaft 514 havingadditional intermediary constraints, balloon inflation causes balloon722 and second deformable guidewire shaft 714B to bend in the samedirection. Distal ends 720A, 720B of first and second deformableguidewire shafts 714A, 714B are thus oriented in different directions,thereby providing two different options or directions to the operator todirect a guidewire inserted through catheter 700. A guidewire may beinserted through guidewire lumen 706A and lumen 716A, or mayalternatively be inserted through guidewire lumen 706B and lumen 716B,thereby obtaining two different opposite directions for the guidewireexiting from catheter 700.

Catheters having a construction which provide an operator with more thanone guidewire direction, such as catheter 600 or catheter 700, areuseful in applications such as a bifurcation or a chronic totalocclusion (CTO). In order to orient a distal end of a balloon catheterin situ, the balloon catheter is percuataneously advanced through avasculature to a target location. The balloon is inflated, and ballooninflation causes the balloon to bend in the first radial direction. Theshaft component selectively bends in either the first radial directionwith the balloon or a second opposing radial direction away from theballoon, thereby selectively orienting the distal end of the shaftcomponent in a direction different from that of the main catheter shaft.More particularly, a method of using catheter 600 at a bifurcation isshown in FIGS. 8A-8C and a method of using catheter 600 to bypass a CTOis shown in FIGS. 9A-9F. Although the methods are illustrated withcatheter 600, it will be understood by those of ordinary skill in theart that the methods may alternatively utilize catheter 100 or catheter700 to direct the catheter distal end in particular direction.

Referring to FIG. 8A, catheter 600 is shown within the vasculature at abifurcation having a main vessel MV, a first branch vessel BV₁, and asecond branch vessel BV₂. The position of catheter 600 within thevasculature and the position of balloon 622 with respect to main shaft602 are visible via radiopaque markers (not shown) on catheter 600. Ifit is desired to direct distal end 620 of catheter 600 towards secondbranch vessel BV₂, as shown in FIG. 8B, first and second magneticcomponents 660, 662 of balloon 622 and deformable guidewire shaft 614,respectively, are not magnetically coupled together. When balloon 622 isinflated as shown in FIG. 8B, balloon 622 and deformable guidewire shaft614 bend in radially opposing directions as described with respect toFIG. 6B. As such, in FIG. 8B, guidewire 860 is shown inserted throughcatheter 600 and extending into second branch vessel BV₂. If it isdesired to direct distal end 620 of catheter 600 towards first branchvessel BV₁, as shown in FIG. 8C, first and second magnetic components660, 662 of balloon 622 and deformable guidewire shaft 614,respectively, are magnetically coupled together. When balloon 622 isinflated as shown in FIG. 8C, deformable guidewire shaft 614 bends inthe same radial direction as balloon 622 as described with respect toFIG. 6A. As such, in FIG. 8C, guidewire 860 is shown inserted throughcatheter 600 and extending into first branch vessel BV₁. Thus, thebending direction of deformable guidewire shaft 614 may be selectivelydecided in situ by the operator, respectively magnetically coupling ordecoupling first and second magnetic components 660, 662, in order todirect the distal end of the catheter towards a particular branch of thebifurcation, i.e., first branch vessel BV₁ and a second branch vesselBV₂.

Referring to FIG. 9A, a guidewire 960 is shown at a portion upstream ofa treatment site, which in this instance is a chronic total occlusionCTO within a lumen 970 of blood vessel V. For purposes of thisdescription, the anatomy of vessel V includes essentially three layers,the tunica intima I (“intima”), tunica media M (“media”) which is thethickest layer of the wall, and the tunica adventitia A (“adventitia”).In some arteries an internal elastic membrane is disposed between themedia M and adventitia A. The adventitia A is made of collagen, vasavasorum and nerve cells, the media M is made of smooth muscle cells, andthe intima I is made up of a single layer of endothelial cells thatprovide a nonthrombogenic surface for flowing blood. In some cases, suchas where blood vessel is totally occluded by hard, calcifiedatherosclerotic plaque, a determinative factor of whether the operatorcan successfully recannalize the CTO is the operator's ability toadvance a guidewire from a position within the true lumen of the mainvessel proximal to the CTO lesion, across the CTO lesion, i.e., eitherthrough the lesion or around it, and then back into the true lumen ofthe main vessel at a location distal to the CTO lesion. One approach ofcrossing a CTO includes creating a neo-lumen called a “subintimal tract”i.e., a penetration tract formed within the wall of the artery betweenthe intima and adventitia. In such instances, after crossing the CTOwithin the subintimal tract, it is necessary to divert or steer theguidewire from the subintimal tract back into the true lumen of theblood vessel at a location distal to the CTO lesion. Although describedin relation to bypassing a CTO, it should be understood that the methodsand apparatus described herein may be used for bypassing any tightstenoses in arteries or other anatomical conduits and are not limited tototal occlusions.

Referring to FIG. 9B, in accordance with techniques known in the fieldof interventional cardiology and/or interventional radiology, a distalend of guidewire 960 pierces the intima I and is advanced distally tocreate a subintimal tract by locally dissecting or delaminating intima Ifrom media M or by burrowing through media M. In order to pierce theintima I, a clinician may manipulate the distal end of guidewire 960 byprolapsing or bending-over the distal end thereof to create a stifferarc or loop 971 that is operable to pierce into the intima I as shown inFIG. 9B. The piercing of the intima I is aided by the fact thattypically blood vessel V is diseased, which in some instances makes theintima I prone to piercing. Alternatively, another device other thanguidewire 960 inserted through catheter 600 may be initially used tocreate the subintimal tract. Those of ordinary skill in the art willappreciate and understand the types of alternative devices that may beused in this step including an apparatus known as an “olive”, a laserwire, an elongate radiofrequency electrode, or any other device suitablefor boring or advancing through the vessel tissue. If an alternativedevice is used instead of guidewire 960 to form the subintimal tract,such alternative device may be removed and replaced with guidewire 960after the subintimal tract has been formed.

Catheter 600 is transluminally advanced over guidewire 960 and withinthe subintimal tract from a near side of the CTO to a position wheredistal end 620 of catheter 600 is positioned in the subintimal tract ona far side of the CTO, as shown in FIG. 9C. Guidewire 960 is partiallywithdrawn until its distal end only slightly extends from distal end 620of catheter 600, or until its distal end is positioned flush with thedistal end 620 of catheter 600. If one or more optional radiopaquemarkers are present which indicate the position of balloon 622 withrespect to main shaft 602, they may be used by the operator to ensurethat catheter 600 is oriented as desired with respect to true lumen 970with deformable guidewire shaft 614 adjacent or next to the true lumen.

Once catheter 600 is positioned within the subintimal tract with distalend 620 downstream of the CTO as desired, first and second magneticcomponents 660, 662 (not shown on FIGS. 9A-9F) of balloon 622 anddeformable guidewire shaft 614, respectively, are magnetically coupledtogether. Once the catheter is positioned and oriented to re-enter thetrue lumen, balloon 622 is inflated as shown in FIG. 9D. Sincedeformable guidewire shaft 614 is magnetically coupled to the balloon,deformable guidewire shaft 614 bends in the same radial direction asballoon 622 as described with respect to FIG. 6A. If the catheter isdisposed in a reverse direction with balloon 622 being positionedbetween deformable guidewire shaft 614 and true lumen 970, first andsecond magnetic components 660, 662 may be decoupled such thatdeformable guidewire shaft 614 bends in an opposite radial directionthan balloon 622 when balloon 622 is inflated. Thus, advantageously,since first and second magnetic components 660, 662 may be coupled ordecoupled in situ, the operator may select or chose which radialdirection to bend deformable guidewire shaft 614 on the basis of how thecatheter is positioned and oriented in the subintimal space at thetarget site. The catheter orientation determines how to operate firstand second magnetic components 660, 662 to have deformable guidewireshaft 614 and balloon 622 bend in the same direction or in radiallyopposing directions. When distal end 620 is bent or deformed to thedesired extent towards lumen 970 of blood vessel V, guidewire 960 ispushed through the intima and into the true lumen of the blood vesseldistal to, i.e., downstream of, the CTO. Guidewire 960 extends in truelumen 970 proximal to the CTO, through the subintimal tract, and backinto true lumen 970 distal to the CTO such that the CTO may now besuccessfully crossed via the subintimal conduit thus created.

Optionally, balloon catheter 600 may be removed and a covered oruncovered stent may be delivered and implanted within the subintimalreentry conduit to facilitate flow from the lumen of the vessel upstreamof the CTO, through the subintimal tract and back into the lumen of thevessel downstream of the CTO. For example, FIG. 9E shows a distal end ofa catheter 972 having a stent 974 mounted thereon being advanced overguidewire 960 to a position where a distal end of the radially collapsedstent 974 is in true lumen 970 of vessel V downstream of chronic totalocclusion CTO, a proximal end of stent 974 is in true lumen 970 ofvessel V upstream of chronic total occlusion CTO, and a mid-portion ofstent 974 extends through the subintimal reentry conduit. Stent 974 isthen deployed by either self-expansion or balloon inflation within thesubintimal reentry conduit to dilate the subintimal reentry conduit andcompress the adjacent chronic total occlusion CTO. Stent 974 provides ascaffold which maintains the subintimal reentry conduit in an opencondition capable of carrying blood downstream of chronic totalocclusion CTO. Thereafter, guidewire 960 and catheter 972 may be removedfrom the patient, leaving stent 974 in an expanded configuration andcreating a radially supported, subintimal blood flow channel aroundchronic total occlusion CTO as seen in FIG. 9F. In some cases, it may bedesirable to enlarge the diameter of the subintimal tract beforeadvancing stent catheter 972 into and through it. Such enlargement ofthe subintimal tract may be accomplished by passing a balloon catheterover guidewire 960 and inflating the balloon to dilate the tract, or maybe any other suitable tract enlarging, dilating or de-bulking instrumentthat may be passed over guidewire 960.

While various embodiments according to the present invention have beendescribed above, it should be understood that they have been presentedby way of illustration and example only, and not limitation. It will beapparent to persons skilled in the relevant art that various changes inform and detail can be made therein without departing from the spiritand scope of the invention. Thus, the breadth and scope of the presentinvention should not be limited by any of the above-described exemplaryembodiments, but should be defined only in accordance with the appendedclaims and their equivalents. It will also be understood that eachfeature of each embodiment discussed herein, and of each reference citedherein, can be used in combination with the features of any otherembodiment. All patents and publications discussed herein areincorporated by reference herein in their entirety.

1-20. (canceled) 21: A balloon catheter comprising: a main cathetershaft including a first guidewire lumen, a second guidewire lumen, andan inflation lumen; a balloon extending from a distal end of the maincatheter shaft, wherein the inflation lumen of the main catheter shaftis in fluid communication with an interior of the balloon; a firstdeformable guidewire shaft extending from a distal end of the maincatheter shaft, adjacent and external to the balloon, wherein the firstdeformable guidewire shaft defines a lumen in fluid communication withthe first guidewire lumen of the main catheter shaft; a seconddeformable guidewire shaft extending from a distal end of the maincatheter shaft, adjacent and external to the balloon, wherein the seconddeformable guidewire shaft defines a lumen in fluid communication withthe second guidewire lumen of the main catheter shaft; a proximal bondthat fixes a proximal end of the balloon to a distal end of the maincatheter shaft; a first distal bond that fixes a distal end of theballoon to a first distal end of the first deformable guidewire shaftand a second distal bond that fixes the first distal end of the firstdeformable guidewire shaft to a second distal end of the seconddeformable guidewire shaft; at least one intermediate bond that fixes anintermediate portion of the balloon to an intermediate portion of thesecond deformable guidewire shaft, wherein an outer surface of the firstdeformable guidewire shaft between the proximal bond and the firstdistal bond is not bonded to the balloon, and wherein the ballooninflation causes the balloon and the first deformable guidewire shaft tobend in radially opposing directions and causes the balloon and thesecond deformable guidewire shaft to bend in the same direction, therebyorienting the distal ends of the first and second deformable guidewireshafts in directions different from that of the main catheter shaft. 22:The balloon catheter of claim 21, wherein a distance between theproximal bond and the distal bond is equal to a length of the balloonprior to inflation thereof. 23: The balloon catheter of claim 21,wherein the guidewire lumen and the inflation lumen are formed bymulti-lumen profile extrusion. 24: The balloon catheter of claim 21,wherein guidewire lumen is defined by a guidewire shaft that extendsthrough the main catheter shaft and the inflation lumen is defined by aninflation shaft that extends through the main catheter shaft and whereina proximal end of the deformable guidewire shaft is coupled to a distalend of the guidewire shaft. 25: The balloon catheter of claim 24,wherein the deformable guidewire shaft includes a coil. 26: The ballooncatheter of claim 24, wherein the deformable guidewire shaft has a lowerbending stiffness than the main catheter shaft such that the maincatheter shaft remains straight during bending of the deformableguidewire shaft. 27: The balloon catheter of claim 26, wherein thebending stiffness of the deformable guidewire shaft is equal to thebending stiffness of the balloon. 28: The balloon catheter of claim 21,further comprising a tubular component which extends through at least aportion of the inflation lumen and includes a distal end that extendsinto the interior of the balloon, wherein a radiopaque marker band ismounted on the distal end of the tubular component. 29: A method oforienting a distal end of a balloon catheter in situ, the methodcomprising the steps of: percuataneously advancing the balloon catheterthrough a vasculature to a target location, wherein the balloon catheterincludes a main catheter shaft, a shaft component extending from adistal end of the main catheter shaft that defines at least one lumen influid communication with a guidewire lumen of the main catheter shaft,and a balloon extending from a distal end of the main catheter shaft,the shaft component extending adjacent and external to the balloon andan inflation lumen of the main catheter shaft being is in fluidcommunication with an interior of the balloon, wherein the shaftcomponent is operable to bend in a first radial direction and a secondopposing radial direction upon balloon inflation; inflating the balloon,wherein balloon inflation causes the balloon to bend in the first radialdirection and causes the shaft component to selectively bend in eitherthe first radial direction with the balloon or the second opposingradial direction away from the balloon, thereby selectively orientingthe distal end of the shaft component in a direction different from thatof the main catheter shaft. 30: The method of claim 29, wherein thetarget location is bifurcation. 31: The method of claim 29, wherein thetarget location is a Chronic Total Occlusion. 32: The method of claim29, wherein the shaft component includes, a first deformable guidewireshaft extending from a distal end of the main catheter shaft, whereinthe first deformable guidewire shaft defines a lumen in fluidcommunication with a first guidewire lumen of the main catheter shaft, asecond deformable guidewire shaft extending from a distal end of themain catheter shaft, wherein the second deformable guidewire shaftdefines a lumen in fluid communication with a second guidewire lumen ofthe main catheter shaft, wherein a proximal bond fixes a proximal end ofthe balloon to a distal end of the main catheter shaft, a first distalbond that fixes a distal end of the balloon to a first distal end of thefirst deformable guidewire shaft, a second distal bond that fixes thefirst distal end of the first deformable guidewire shaft to a seconddistal end of the second deformable guidewire shaft, an outer surface ofthe first deformable guidewire shaft between the proximal bond and thefirst distal bond is not coupled to the balloon, and at least oneintermediate bond fixes an intermediate portion of the balloon to anintermediate portion of the second deformable guidewire shaft, andwherein the step of inflating the balloon causes the balloon and thefirst deformable guidewire shaft to bend in radially opposing directionsand causes the balloon and the second deformable guidewire shaft to bendin the same direction, thereby orienting the distal ends of the firstand second deformable guidewire shafts in directions different from thatof the main catheter shaft. 33: The method of claim 29, wherein theshaft component is a single deformable guidewire shaft, a proximal bondfixes a proximal end of the balloon to a distal end of the main cathetershaft, a distal bond fixes a distal end of the balloon to a distal endof the deformable guidewire shaft, an outer surface of the deformableguidewire shaft between the proximal bond and the first distal bond isnot bonded to the balloon, and the balloon catheter further includes afirst component coupled to or insertable within or over an intermediateportion of the balloon, and a second component coupled to or insertablewithin or over an intermediate portion of the deformable guidewireshaft, wherein the first and second components are operable toselectively and temporarily couple the intermediate portion of theballoon and the intermediate portion of the deformable guidewire shafttogether, and wherein the step of inflating the balloon causes theballoon and the deformable guidewire shaft to bend in radially opposingdirections when the intermediate portions of the balloon and deformableguidewire shaft are not coupled together and causes the balloon and thedeformable guidewire shaft to bend in the same direction when theintermediate portions of the balloon and deformable guidewire shaft arecoupled together. 34: A balloon catheter comprising: a main cathetershaft including a guidewire lumen and an inflation lumen; a balloonextending from a distal end of the main catheter shaft, wherein theinflation lumen of the main catheter shaft is in fluid communicationwith an interior of the balloon; a deformable guidewire shaft extendingfrom a distal end of the main catheter shaft, adjacent and external tothe balloon, wherein the deformable guidewire shaft defines a lumen influid communication with the guidewire lumen of the main catheter shaft;a proximal bond that fixes a proximal end of the balloon to a distal endof the main catheter shaft; a distal bond that fixes a distal end of theballoon to a distal end of the deformable guidewire shaft, wherein anouter surface of the first deformable guidewire shaft between theproximal bond and the first distal bond is not bonded to the balloon; afirst component coupled to or insertable within or over an intermediateportion of the balloon; and a second component coupled to or insertablewithin or over an intermediate portion of the deformable guidewireshaft, wherein the first and second components are operable toselectively and temporarily couple the intermediate portion of theballoon and the intermediate portion of the deformable guidewire shafttogether, wherein balloon inflation causes the balloon and thedeformable guidewire shaft to bend in radially opposing directions whenthe intermediate portions of the balloon and deformable guidewire shaftare not coupled together and causes the balloon and the deformableguidewire shaft to bend in the same direction when the intermediateportions of the balloon and deformable guidewire shaft are coupledtogether, thereby selectively orienting the distal end of the deformableguidewire shaft in a direction different from that of the main cathetershaft. 35: The balloon catheter of claim 34, wherein a distance betweenthe proximal bond and the distal bond is approximately equal to a lengthof the balloon prior to inflation thereof. 36: The balloon catheter ofclaim 34, wherein the guidewire lumen and the inflation lumen are formedby multi-lumen profile extrusion. 37: The balloon catheter of claim 34,wherein guidewire lumen is defined by a guidewire shaft that extendsthrough the main catheter shaft and the inflation lumen is defined by aninflation shaft that extends through the main catheter shaft and whereina proximal end of the deformable guidewire shaft is coupled to a distalend of the guidewire shaft. 38: The balloon catheter of claim 34,further comprising a tubular component which extends through at least aportion of the inflation lumen and includes a distal end that extendsinto the interior of the balloon, wherein a radiopaque marker band ismounted on the distal end of the tubular component.